title: Formation of the digestive tract in Ciona intestinalis includes two distinct morphogenic processes between its anterior and posterior parts.
abstract: BACKGROUND
  In the ascidian Ciona intestinalis, the digestive tract, an essential system for animals, develops during metamorphosis from the two primordial tissues, the endoderm and endodermal strand, located in the larval trunk and tail, respectively. However, it has been largely unknown how the digestive tract develops from these primordial tissues. We examined the metamorphosing larvae for the tubular formation of the digestive tract, focusing on the epithelial organization of the endoderm, by combined confocal microscopy and computational rendering.
  
  
  RESULTS
  The tubular structure of the esophagus to the stomach was formed through the folding and closure of the endodermal epithelia in the central-to-right posterior trunk. By contrast, the intestine was formed in the left posterior trunk through the accumulation and rearrangement of the cells originated from the endodermal strand. This was confirmed by the cell-tracing experiment using Kaede expression construct driven in the endodermal strand. Thus, the tubular formation of the digestive tract in C. intestinalis includes distinct morphogenetic processes and cell lineages between its anterior and posterior parts.
  
  
  CONCLUSIONS
  This study provides the first detailed description of the digestive tract morphogenesis in C. intestinalis and serves as an important basis toward thorough understanding of its digestive tract development.
authors.affiliation: Department of Biological Sciences, Graduate School of Science and Engeneering, Tokyo Metropolitan University, Hachiohji, Tokyo, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Nakazawa
authors.forename: Takumi
authors.initials: T
authors.lastname: Yamazawa
authors.forename: Yuuta
authors.initials: Y
authors.lastname: Moriyama
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Ogura
authors.forename: Narudo
authors.initials: N
authors.lastname: Kawai
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Sasakura
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Saiga
mesh_terms: D000818:Animals; D002938:Ciona intestinalis / Q000166:cytology / Q000196:embryology*; D004064:Digestive System / Q000166:cytology / Q000196:embryology*; D007814:Larva / Q000166:cytology / Q000502:physiology; D008675:Metamorphosis, Biological / Q000502:physiology*
keywords: Ascidian; Ciona intestinalis; Digestive tract morphogenesis; Endoderm; Endodermal strand